Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2014

Fair Value of Financial Instruments

Schedule of fair value of financial assets and liabilities measured at fair value and classification by level of input

	Fair Value Measurements as of
	March 31, 2014
(in thousands)	Level 1		Level 2		Level 3		Total
Investments:
Money market funds	$	33,137	$	—	$	—	$	33,137
Commercial paper	—		10,247		—		10,247
Corporate debt securities	—		20,747		—		20,747
Total investments	$	33,137	$	30,994	$	—	$	64,131

	Fair Value Measurements as of
	December 31, 2013
(in thousands)	Level 1		Level 2		Level 3		Total
Investments:
Money market funds	$	53,511	$	—	$	—	$	53,511
Federal agency securities	—		12,301		—		12,301
Commercial paper	—		8,249		—		8,249
Corporate debt securities	—		1,961		—		1,961
Total investments	$	53,511	$	22,511	$	—	$	76,022